The present invention relates to a mechanism for driving a tape at a constant speed in a tape drive. For new high density digital tape recorders which need to run the tape at constant low speed, typically 5-10 cm/sec, this has been heretofore accomplished with a fly wheel capstan, and a pressure roller.
In prior art tape drives which use a capstan and pressure roller, the tape is moved with the speed of the capstan surface. Typical examples of such drives include video recorders, 4 millimeters and 8 millimeters tape drives, and some audio open reel recorders. Such drives are disclosed for example in U.S. Pat. Nos. 4,984,111; 5,323,280; and 3,692,255.
Low speed video tape drives can include the capstan and pressure roller arrangement for translating the tape at a constant speed in addition to a means of turning the reels to wind the tape, such as described in U.S. Pat. Nos. 4,190,869 and 4,390,909.
It is also known to control tape speed by direct tape speed measurement, such as by a roller, and issuing a correction signal to a take up reel motor such as disclosed in 5,491,594; 4,696,439 or 4,514,672; or by calculating tape speed by a reel tachometer and applying correction signals to the take up reel motor such as in U.S. Pat. No. 4,531,166.